Power quality has become increasingly important for industrial and commercial electric power customers, particularly as today’s manufacturing and control processes rely on computerized equipment which is sensitive to power system interruptions and disturbances. 

Eltec International can provide solutions to existing power quality problems, alleviate problems that may be looming in a power system, and provide recommendations to ensure optimal power quality for facilities under construction or renovation.

Power quality problems can affect your productivity and your bottom line. We have the experience, know-how, and technology to identify, solve, and oftentimes prevent problems. Our services, including site surveys, computer simulations, and equipment sensitivity assessments are invaluable tools for improving power system performance.

Common Power Quality Problems

Through our work with all sorts of facilities, we've identified three significant types of power quality problems that can impact customer operations:

• Voltage Sags and Momentary Interruptions. Increased sensitivity of power electronic equipment, coupled with the high likelihood of voltage sags and interruptions, has resulted in these being the most common power quality problem. Variable Frequency drives, computers, office equipment, programmable controllers, and induction heating furnaces can be extremely sensitive to these events. Typically, sags occur when there are temporary faults on the utility power system, resulting in a reduction in the voltage level. Equipment sensitivity to these events is important because nuisance tripping of sensitive industrial loads can cause equipment downtime, reduce productivity, and hurt your bottom line.
• Transients. These are power quality disturbances that involve destructive high magnitudes of current and voltage or even both. It may reach thousands of volts and amps even in low voltage systems. However, such phenomena only exist in a very short duration from less than 50 nanoseconds to as long as 50 milliseconds.AC and DC drives, along with other electronic loads, can be very sensitive to transient voltages. The tolerance levels of these devices are often less than other loads such as standard motors. A major concern for transient voltages occurs with possible magnification of utility capacitor switching transients at low-voltage capacitor locations on customer power systems.
• Harmonics. Adjustable-speed and dc drives, along with switch-mode power supplies, cause harmonic currents due to their nonlinear characteristics. These harmonic currents can combine with system frequency response characteristics to cause harmonic voltage distortion. This distortion can cause control malfunction, capacitor failures, motor and transformer overheating, and increased system losses. These problems are compounded by the use of capacitor banks, which can cause resonance conditions magnifying the harmonic distortion levels. . IEEE's Std. 519 specifies strict current distortion limits that can prove difficult to comply with.

While we do facility power system studies, we look at a range of specific issues, such as:

• Harmonic analysis
• Transient analysis
• Utility capacitor switching activities
• Voltage variation analysis
• Power factor correction

Solving PQ Problems

Eltec International uses a wide range of techniques and tools to find, study, and correct power quality problems. Monitoring and field measurements are a key element in the problem-solving process. We use a combination of fixed and portable monitoring instruments to detect and analyse disturbances on both the utility and consumer side, as well as at key process points and other locations. This monitoring helps us to locate where problems are occurring, and determine their potential cause(s) and solution(s).

We also use computer based simulation software to model your power system and to perform "what if" analyses to determine power system vulnerability and identify potential problems, as well as possible solutions. We verify the software simulated model against the measurement results.

Our goal is to prescribe solution that is effective, cost-efficient, and won't cause problems for either you or the utility. We look at a wide range of corrective measures, including, to providing a range of cost-effective options for mitigation.

• Active and Passive Harmonic filters
• Capacitors with detuned reactors
• Harmonic Mitigation Transformers
• Surge arrestors or protectors
• Uninterruptible power supplies (UPS)
• Energy Storage Systems
• Backup generation

How Power Quality Can Impact You

The question "What is power quality?" has many different answers, depending on whether you talk to utilities, equipment manufacturers, or power customers. There is a wide range of factors that can cause power quality problems in your facility. Our experience has shown that power quality problems are compounded by the difficulty of identifying potential causes. This is primarily because the cause may be within your facility or hundreds of miles away on the utility power grid. Power quality investigations focus on the cost impact of power problems. These can include

• Facility or equipment downtime
• Scrapping of products and raw materials
• Process or equipment restart
• Repair or replacement of damaged machines and equipment
• Operating at less than optimal efficiency
• Increased utility demand charges

Each problem can generate a number of these costs. Predicting the exact cost is difficult, but poor power quality and poor power system performance can cause sufficient losses to justify fixing the problem.